Microwave phase shifters are radio frequency (RF) circuit networks that are used to introduce variable phase delays to RF signals. Their most important application is phased array systems that are typically constructed as one-dimensional or two-dimensional periodic arrangements of multiple individual antenna elements integrated with microwave phase shifters. These systems can electronically steer the direction of maximum or minimum radiation by utilizing the phase shifters to adjust the phase delays between the waves emitted from the individual antenna elements. Therefore, microwave phase shifters play a key role for the cost, efficiency, gain, and bandwidth performance of such phased array systems.
A significant problem related to the design of microwave phase shifters is achieving designs that can provide a constant phase shift over a broad frequency range while maintaining excellent impedance match in each state of the phase shifter. In addition, maintaining the component size and keeping its insertion loss low are also design challenges.